This invention relates to systems for bringing the frequency of an oscillator under the control of the frequency of the carrier of a pulse of very brief duration.
This is a problem arising in the receivers of systems providing electromagnetic detection of very brief pulses where pulse frequency varies between individual pulses, for in such cases the local oscillator frequency of the receiver must also vary but under the control of the variation in the frequency of the pulse, so that the receiver intermediate frequency remains close enough to its rated value to be compatible with the receiver pass band.
The known techniques can provide such a form of control for the duration of the pulse but cease to be satisfactory for pulse duration below 1 microsecond.
The control system according to the invention is of use for much shorter pulses, for instance, lasting 0.25 microseconds.